The present invention relates generally to methods of measuring small distances between, and for measuring the flatness of, electrically conductive surfaces. More particularly, the present invention relates to using the Casimir force to measure small distances between, and to measure the flatness of, electrically conductive surfaces.
Electronic and mechanical devices of all kinds are becoming smaller, thus requiring continually increasing precision in their manufacture. The resolution required for the manufacturer of certain devices at times approaches the nanometer level. Moreover, this resolution is being required over larger and larger distances, so that many devices can be made in a single manufacturing operation. Measurement of very small distances are frequently required in applications involving nanotechnology, which is the synthesis and integration of material, processes and devices in sub-micrometer size range. In the past few years, computer technology has experienced miniaturization and power previously believed impossible. Mass storage devices are one of many components of modern computers. One type of mass storage device is the fixed disc drive. Such drives are used to store vast amounts of information relating to operating systems, applications, and user data. Precision measurement needs for disc drives are increasing with the miniaturization of disc drive components.
In the field of very small (less than approximately 500 Angstroms) distance measurement, some prior systems employ light interferometry to measure the distance between two very closely spaced surfaces. Other systems use electrostatic or capacitive techniques. These systems begin to lose capability as the distance being measured approaches the point of contact. Interferometry techniques lose capability at very small distances because the shortest wavelength of visible light is too wide to be efficiently used to make measurements of very small distances. Electrostatic and capacitive techniques are hindered by the fact that charge transfer (arcing) occurs from one surface to the other at very close distances and metallic contact point conduction occurs upon the contact of metallic surfaces.
The present invention addresses these problems and offers other advantages over the prior art.
The present invention relates to the measurement of very small distances between, and the flatness of, electrically conductive surfaces.
One embodiment of the present invention relates to a method of measuring the distance between first and second proximately disposed electrically conductive surfaces. The method includes measuring the force exerted between the first and second surfaces to obtain an exerted force value, and determining a separation distance between the first and second surfaces as a function of the exerted force value.
Another embodiment of the present invention relates to a method of determining the degree to which the shape of a first electrically conductive surface varies from a nominal shape. The method includes holding the first surface a known separation distance from a second electrically conductive surface having a known shape. The force exerted between the first and second surfaces is measured to obtain an exerted force value. The measured exerted force value is compared to a nominal force value that would be expected to be exerted between the first and second surfaces as a result of the Casimir force if the shape of the first surface were equivalent to the nominal shape. A difference between the measured exerted force value and the nominal force value is obtained.
These and various other features as well as advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.